COVID-19 in South Korea - and potential implications for us (wherever we are)
(Updated: 2020-03-30 17:18:23 EST)
So, I have been watching the epidemic in China and Korea since the beginning, but it is still not easy to settle into this reality here in the US.
First of all, everyone, STAY HEALTHY and see what YOU can do!
Second, there are many excellent news articles and information sources, but I’m sharing some more questions (see left panel) and answers for those who are curious about the situation in South Korea, specifically. Please note that the country has had a trace-test-isolate strategy consistently from the outset of this epidemic. If you want to know more about South Korean situation - compared to other countries, see this Washington Post article: How countries arond the world have tried to contain the coronavirus
All data are from press release from KCDC - available to the public in both Korean and English. Kudos!
Q 8. Is it spreading faster in some age groups than others?
So, we know about the age-pattern of mortality (i.e., higher in older ages, see Question 4) and relatively young patient population in South Korea (See Question 3). Meanwhile, as I saw overall mortality going up steadily (See Question 7.1), I wanted to know if COVID is spreading more rapidly among those who would have higher mortality risk (e.g., older people). One way to answer that question is to see if infection incidence rate (number of confirmed cases per population) has increased more rapidly in one age group than others.
In all age groups, there was a rapid increase in early March, when the country had a huge and acute outbreak (sorry, it’s not very clear in the figure, because the age-specific trend data starts from March 3rd). Following that, however, the infection rate has increased more rapidly among those who are 80 and older than in any other age groups (red line in the below figure): from 6 per 100,000 people on March 3rd when detailed data by age were released first, to 17 on March 19th, and 23 on March 29th. This may be due to recent outbreaks in nursing homes.
Hover over each figure to see values and more options.
(Source: KCDC’s daily press release, and UN World Population Prospects 2019 Revision)Note: Age-specific data were first released on March, 3rd, and it has been updated daily since March 11th.
Q 7.1. How has mortality changed over time?
South Korea had the first COVID death on February 19th. As of 2020-03-30, there have been a total of 158, with an overall mortality rate of 1.6% among all cases.
The below graph shows trend of the overall mortality rate (starting from February 21st). The mortality rate (orange bars) initially increased for several days, but, as the number of new cases increased exponentially (see gray bars also Question 2), the mortality rate declined after the first peak. Then, it has increased gradually to the current level. Since South Korea still has been able to continue the trace-test-isolate strategy, it will be important to monitor mortality trends, providing important insight about this epidemic.
Hover over each figure to see values and more options.
(Source: KCDC’s daily press release, and UN World Population Prospects 2019 Revision)Q 7.2. How has mortality changed over time, by age group?
The graph below shows trends of mortality by age group - starting from March 3rd. Mortality among those 80 and above has increased continuously. As of 2020-03-30, 18.3% of people in their 80s who have confirmed COVID have died, increaed from 5.6% on 2020-03-03. This increase is not surprising, considering the typical clinical timeline and prognosis of COVID infection. A more important question is if and when the mortality rate will level off, as this epidemic progresses and a bigger proportion of population is affected.
Mortality rate among the 70s has also increased but at a slower margin. Mortality among those in their 50s and 60s have remained similar over time or increased slowly.
Hover over each figure to see values and more options.
(Source: KCDC’s daily press release, and UN World Population Prospects 2019 Revision)Note: Age-specific mortality data were first released on March, 3rd, and it has been updated daily since March 11th.
Q 6. How is it affecting children?
Compared to other age groups, incidence rates are much lower among those under 20 (See Question 3). There have been 0 deaths reported in these age groups, and mortality rates are also the lowest among all age groups (See Question 4).
Still, new detailed data from Korea CDC give some information about cases among children younger than 18 years of age. As of 2020-03-17, incidence rate by detailed age group is shown below. Older children have higher infection rates.
Hover over each figure to see values and more options.
(Source: KCDC’s daily press release on 2020-03-17, and UN World Population Prospects 2019 Revision)Note: These age groups roughly corresponds with school system age groups in South Korea.
Of course, this is only epidemiologic perspective. Children’s emotional, social, and economic well-being is more complex and difficult to capture yet.
Q 5. How extensive has testing been?
Very aggressive. As of 2020-03-30, a total of 395 thousand people have been tested. There are 51 million people in the country, and 8 in every 1000 people have been test. This is the second highest testing rate in the world, following United Arab Emirates. Epidemiological investigation of the case No. 31 (who was confirmed on February 18th) prompted immediate and massive testing in Daegu and nation wide.
(Source: KCDC’s daily press release. The number of tests is calculated based on the daily increase in the total number of tests reported.)Q 4. What is the mortality - overall and by age group?
Among those who have COVID, mortality rate among the elderly with COVID is very high: 18.3% for those who are 80 or older, and 7% for those who are between 70-79.
Again, this is the case under a very aggressive trace-test-isolate strategy, but with no nation wide lock down. As of 2020-03-30, a total of 158 people with COVID have died, 1.6% among all COVID cases. These rates - overall as well as by age group - are lower than mortality rates in China.
There are news articles about extremely over-burdened health systems especially in Daegu. I’ve read a few mortality case on the newspaper while he/she was waiting for hospital admission, and patients from Daegu and a surrounding province being transferred to other less-affected provinces. However, my impression (as a public health trained reader) is that most severe cases do receive treatment at hospitals. I’m looking for more systematic data on health systems’ capacity and response.
Q 3. What age groups are affected?
For this question, let’s look at the total cumulative number of confirmed cases since the outbreak per 100,000 population by age group, not the absolute number. Also, keep in your mind, this is what we see under a very aggressive trace-test-isolate strategy (see this and this). Finally, KCDC releases the number by 10-year age group, and I’m following that categorization.
- Incidence rate is substantially high in the 20s: 39 people have been infected per 100,000 population in their 20s. At least partially, this is reflection of a very concentrated epidemic in Daegu related to a church, and the age pattern among the church attendants. So this age pattern may not be relevant for more generalized pandemic situation.
- Incidence rate among those under 20 is low. It may indicate either children are less susceptible, and/or - more importantly - they have been protected at home since all Korean schools have been in long winter break (typically over several weeks) or under temporary closure since the end of December, 2019.
Q 2. How fast has it been spreading?
For this question, let’s focus on the number of new cases by day. For about a month, only 30 cases were confirmed - mostly in/near Seoul. However, starting from the case No. 31 (a super transmitter who was confirmed on February 18), the number of new cases exponentially increased - primarily in Daegu and a region surrounding it but throughout the country. For 10 days, more than 400 new cases were confirmed everyday, with a peak of 909 new cases on February 29. More recently, the number of new cases started to decrease (see below). Still, as of 2020-03-30, a total of 9661 people have been infected.
(Source: KCDC’s daily press release on 2020-03-30)In Daegu, where about three quarters of the cases are concentrated, the daily number of new cases has decreased clearly. 
(Source: Figure from KCDC’s daily press release, “Updates on COVID-19 in Korea (as of 19 March)”)
But, COVID can and does continue to spike up. In Seoul, there was a peak around the same time with the sharp epidemic in Daegu, followed by several days with much lower number of or no new cases. But, there seems to be a specific call-center related epidemic, as shown in the sudden increases in the number of new cases around March 11th.
(Source: Figure from KCDC’s daily press release, “Updates on COVID-19 in Korea (as of 19 March)”)
Q 1. When did it start?
On January 20, 2020, there was the first laboratory confirmed COVID case.
More questions and data coming soon, as I continue digging the awesome KCDC website…
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